Cluster validity indices for mixture hazards regression models.

In the analysis of survival data, the problems of competing risks arise frequently in medical applications where individuals fail from multiple causes. Semiparametric mixture regression models have become a prominent approach in competing risks analysis due to their flexibility and easy interpretation of resultant estimates. The literature presents several semiparametric methods on the estimations for mixture Cox proportional hazards models, but fewer works appear on the determination of the number of model components and the estimation of baseline hazard functions using kernel approaches. These two issues are important because both incorrect number of components and inappropriate baseline functions can lead to insufficient estimates of mixture Cox hazard models. This research thus proposes four validity indices to select the optimal number of model components based on the posterior probabilities and residuals resulting from the application of an EM-based algorithm on a mixture Cox regression model. We also introduce a kernel approach to produce a smooth estimate of the baseline hazard function in a mixture model. The effectiveness and the preference of the proposed cluster indices are demonstrated through a simulation study. An analysis on a prostate cancer dataset illustrates the practical use of the proposed method.

Assessment of treatment outcomes of interstitial cystitis with hydrodistention and bladder training by O'Leary-Sant Interstitial Cystitis Symptom and Problem Indices.

OBJECTIVE: To investigate whether the O'Leary-Sant Interstitial Cystitis Symptom Index (ICSI) and Interstitial Cystitis Problem Index (ICPI) is efficacy measure tool for interstitial Cystitis (IC) treatment with hydrodistention (HD) and bladder training (BT). MATERIALS AND METHODS: From January 2003 to March 2006, 108 consecutive IC patients were treated by HD and BT after HD. This study evaluated the efficacy of treatment with the specific questionnaire for IC, the ICSI and ICPI. Each patient filled out the questionnaire before HD and three months after HD and BT. The efficacy of the treatment was evaluated using the average scores of ICSI and ICPI. RESULTS: The mean ± margin of error, (95% confidence interval) of total scores of ICSI and ICPI were 13.89 ± 2.95, (13.33-14.45) and 12.51 ± 2.50, (12.04-12.98) before HD, respectively, and were 2.70 ± 1.16, (2.44-2.95) and 1.99 ± 1.27, (1.71-2.26) (all p < 0.005) three months after HD and BT, respectively. CONCLUSION: O'Leary-Sant ICSI and ICPI is not only a screening tool for IC but also a useful assessment tool for IC treatment outcomes.

Effects of parity and mode of delivery on urinary incontinence among postmenopausal women in Taiwan.

OBJECTIVE: To investigate the association between the prevalence of urinary incontinence and parity or mode of delivery among Taiwanese women aged 60 years or older. METHODS: Between July 1999 and December 2000, a nationwide epidemiologic study was conducted in Taiwan among 2410 women selected by a multistage random sampling method. Face-to-face interviews with 1517 women were conducted. The relationship between the prevalence of urinary incontinence and the number of vaginal deliveries or number of cesarean deliveries was assessed by frequency and Pearson χ(2) test using a significance level of less than 0.05. Logistic regression was used to investigate the significance of dichotomous dependent variables. RESULTS: Decades ago, most Taiwanese women (1435 of 1511 respondents, 94.97%,) gave birth via vaginal delivery and the rate of cesarean delivery was low (20 of 1513 respondents, 1.32%). Parity (odds ratio [OR], 2.42; 95% confidence interval [CI], 0.87-6.71; P=0.091), vaginal delivery (OR, 0.76; 95% CI, 0.39-1.47; P=0.408), and cesarean delivery (OR, 1.47; 95% CI, 0.59-3.70; P=0.409) did not increase the risk of urinary incontinence. CONCLUSION: There was no association between urinary incontinence and parity or mode of delivery among Taiwanese postmenopausal women decades after their first delivery.

Hydrodistention plus bladder training versus hydrodistention for the treatment of interstitial cystitis.

OBJECTIVE: To assess the efficacy of hydrodistention (HD) followed by bladder training (BT) versus HD alone in patients with interstitial cystitis (IC). METHODS: A total of 70 patients with IC were included and randomly assigned to two groups: one treated with HD (HD group) and the other treated with HD plus BT (HD plus BT group). Each patient was followed up using a weekly diary for 8 weeks after HD and monthly thereafter for 6 months after HD. Evaluation parameters included age, duration of IC in years, how many doctors visited before treatment, urgency, bladder pain, daytime voided volume per void, nocturnal volume per void, daytime voids per day, and nocturia per day. RESULTS: Age, duration of IC in years, doctors visited before treatment, and voiding profiles of patients before treatments between the two groups did not show statistical significance. However, at 24 weeks after HD, the proportions of urgency, and bladder pain of the HD group versus the HD plus BT group were 43.48% versus 10.71% (p = 0.008), and 34.78% versus 14.29% (p = 0.086), respectively. Concurrently, the mean ± standard deviation of daytime voided volume per void, nocturnal volume per void, daytime voids per day, and nocturia per day of the HD group and HD plus BT group are 212.2 ± 114.2 mL and 300.1 ± 90.2 mL (p = 0.005), 276.8 ± 113.0 mL and 360.0 ± 129.6 mL (p = 0.018), 8.2 ± 3.2 and 6.2 ± 1.4 (p = 0.010), and 2.2 ± 1.2 and 1.5 ± 0.7 (p = 0.019), respectively. CONCLUSION: HD followed by BT produced a statistically significantly better effect than HD alone in the treatment of patients with IC.

Long-term effect of hysterectomy on urinary incontinence in Taiwan.

OBJECTIVE: To investigate the effect of hysterectomy on urinary incontinence (UI) in Taiwanese women aged 60 or older. MATERIALS AND METHODS: A nationwide epidemiologic study was conducted and a total of 2410 women were selected by a multistage random sampling method. Face-to-face interviews with 1517 women were completed. The prevalence of UI by hysterectomy, route of hysterectomy, medical reasons for hysterectomy, and years after hysterectomy were assessed by frequency and Pearson's χ(2) test using a significance level of less than 0.05. RESULTS: The prevalence of hysterectomy in Taiwanese women aged 60 or older was 8.83% (134/1,517). Hysterectomy is a risk factor of UI (p=0.003) with the prevalence of UI estimated to be 42.38% (59/134) and that of nonhysterectomy group to be 27.96% (425/1380). Route of hysterectomy (p=0.825), reason for hysterectomy (p=0.060), and how many years after hysterectomy has been performed (p=0.562) were not associated with deteriorating symptoms of UI. CONCLUSION: There is a high prevalence of UI among women who have performed hysterectomy, but there is no significant relationship between UI and route of hysterectomy, reason for hysterectomy, including cervical cancer and uterine prolapsed, or year after hysterectomy.

Risk factors of urinary frequency among women aged 60 and older in Taiwan.

OBJECTIVE: To assess the associated risk factors for daytime urinary frequency among Taiwanese women aged = 60 years. MATERIALS AND METHODS: Daytime urinary frequency, defined by the International Continence Society, and its associated problems were evaluated, and medical history and sociodemographic variables were recorded. A total of 2,410 women were selected by a multistage random sampling method. The factors were assessed by frequency and Pearson's ?2 test using a significance level of < 0.05. RESULTS: A total of 621 women of those initially selected in the study died before completion of this study. Face-to-face interviews with 1,521 women were completed, producing a response rate of 85.0% (1,521/1,789 women). The prevalence of daytime urinary frequency was significantly related to body mass index (p = 0.018), diabetes mellitus (p = 0.017), hypertension (p = 0.015), previous drug allergy (p = 0.003), smoking (p = 0.005), hormone therapy (p = 0.019), parity (p = 0.019), and urinary incontinence (p = 0.000). However, there was no association between urinary frequency and previous gynecologic surgery, hysterectomy, alcohol consumption, marital status, childbirth, and age of menopause. CONCLUSION: The results of this study showed a relatively high risk of urinary frequency development in patients with urinary incontinence, diabetes mellitus, hypertension, obesity, and smoking that are preventable, modifiable, or controllable. Better quality of health education for these women, drawing their attention to the associated factors, may have an impact on the prevalence of urinary frequency.

Prevalence of urinary frequency among women aged 60 years and older in Taiwan.

OBJECTIVE: To evaluate the prevalence of daytime urinary frequency among Taiwanese women aged 60 years and older. MATERIALS AND METHODS: There were an estimated 1.25 million female residents aged 60 years and over in Taiwan in 2000. A sample of 2,410 women was selected using a multistage random sampling method. Face-to-face visits with 1,523 women were completed by trained professional interviewers within 3 months of the subjects selection. Questions about urinary frequency and other lower urinary tract symptoms, sociodemographics, reproduction, and medical and surgical histories were recorded. The factors were assessed by frequency and Pearson's Chi-squared test using a significance level of < 0.05. RESULTS: The prevalence of urinary frequency in Taiwanese women aged 60 years and over was 18.8% (286/1,521). The response rate was 85.0% (1,521/1,789). For those who complained of frequency, 45.8% voided 8-15 times a day, 37.8% voided 16-23 times a day, 1.7% voided 24-31 times and a day, and 14.7% voided more than 31 times a day. The prevalence of urinary frequency was significantly associated with age (p < 0.001). CONCLUSION: Urinary frequency is a common symptom in menopausal women and is significantly related to age. More than half of the women interviewed experienced intervals of < 1 hour between visits to the restroom during the day.

Risk factors for urinary incontinence in Taiwanese women aged 20-59 years.

OBJECTIVE: To assess the risk factors for urinary incontinence among Taiwanese women. MATERIALS AND METHODS: A sample of 4,549 women was selected using a multistage random sampling protocol. The women selected were interviewed face-to-face by well-trained interviewers. The usual risk factors, which included marital status, age, body mass index, menstrual status, alcohol intake, drug allergy, diabetes mellitus, hypertension and gynecologic events, were evaluated. The factors were assessed by frequency analysis and logistic regression analysis using a significance level of less than 0.05. RESULTS: A total of 3,537 women were successfully interviewed, producing a response rate of 77.8% (3,735/4,549). The prevalence of urinary incontinence increased significantly with marriage (21.7%; 95% confidence interval, CI, 20.2-23.2), alcohol intake (24.9%; 95% CI, 19.3-30.5), drug allergy (24.5%; 95% CI, 19.9-29.2), diabetes mellitus (40.3%; 95% CI, 29.3-51.2), hypertension (30.1%; 95% CI, 23.8-36.4), body mass index (odds ratio, 1.05 per unit increase; 95% CI, 1.02-1.09) and a previous gynecologic operation (25.5%; 95% CI, 19.9-31.2). Age was also a risk factor for urinary incontinence (odds ratio, 1.04; 95% CI, 1.03-1.05), but there was no relationship between urinary incontinence and parity, route of delivery, smoking or menstrual status. CONCLUSION: There is a high prevalence of urinary incontinence among women who suffer from diabetes or hypertension, or who have undergone a gynecologic operation, in particular hysterectomy. From a public health viewpoint, it is important to promote better health education in order to improve understanding of urinary incontinence and its risk factors and to increase the awareness of the availability of mainstream treatments.

Nocturia among women aged 60 or older in Taiwan.

BACKGROUND: From a public health point of view, it is important to evaluate the prevalence of nocturia and to identify the associated factors for nocturia among the elderly that might impair the quality of life of sufferers. However, those among the Taiwanese female population aged 60 or older are still unclear. AIMS: To estimate the prevalence of nocturia in Taiwanese women aged 60 or older and to assess its associated factors. METHODS: Nocturia, defined by the International Continence Society, and its associated problems were evaluated, and medical history and sociodemographic variables were recorded. A sample of 2410 female was selected by a multistage random sampling method. RESULTS: Six hundred and twenty-one women who were selected had been deceased. Face-to-face interviews with 1523 women were completed, producing a response rate of 85.1% (1523 of 1789) and 73.5% (1120 of 1523) of the interviewees reported having had nocturia. Age, diabetes mellitus, hypertension, prior drug allergy and urinary incontinence significantly increased the risk of nocturia. CONCLUSIONS: Although the pathophysiologies of nocturia are still not all known, it is a common condition among Taiwanese women. Multiple approaches are necessary to treat the patients with nocturia. Treatment of nocturia in this patient population can both improve their quality of life and reduce the risk of deterioration in their general state of health.

Treatment of interstitial cystitis with hydrodistention and bladder training.

This study aimed to evaluate the efficacy of hydrodistention (HD) and bladder training for interstitial cystitis (IC). From 1997 to 2006, 361 consecutive IC patients were treated by HD, followed by bladder training. Each patient was followed up using a diary for 8 weeks after HD weekly and monthly thereafter. The efficacy of the treatment was evaluated using the average of the voided volumes and the voiding frequency. The mean +/- standard deviation of the pre-HD daytime voided volumes and voiding frequency were 110.0 +/- 47.0 ml and 14.7 +/- 11.0, respectively. Furthermore, the nocturnal values were 173.1 +/- 91.8 ml and 2.8 +/- 1.7, respectively. After 72 weeks post-HD, the 185 patients who completed the follow-up had volumes/frequency of daytime, 306.5 +/- 80 ml and 6.9 +/- 2.1, respectively, and nocturnal, 325.8 +/- 122.4 ml and 1.3 +/- 0.6, respectively. The implementation of HD and bladder training is crucially important for long-term remission among IC patients.

Prevalence of and attitude toward urinary incontinence in postmenopausal women.

OBJECTIVE: To investigate the prevalence of urinary incontinence, and the knowledge, attitudes, and practices of Taiwanese women aged 60 years or older. METHOD: A nationwide epidemiological study was conducted and a sample of 2410 women was selected. Personal visits to 1517 women were completed. RESULTS: A total of 485 (29.8%) women reported urinary incontinence; 250 (69.9%) urinary incontinent women experienced symptoms less than once a month. Regarding knowledge, attitudes, and practices, 822 (54.3%) of the women surveyed knew the meaning of urinary incontinence, and 147 (30.3%) with urinary incontinence had visited a doctor. The main reason given for not seeking medical help was shyness. CONCLUSION: Although urinary incontinence is a common symptom, it is often not reported to doctors, which leads to undertreatment. From a public health perspective, there is considerable opportunity to improve women's quality of life by increasing health education about urinary incontinence and its treatment.

Risk factors for urinary incontinence in Taiwanese women aged 60 or over.

To determine risk factors of urinary incontinence (UI) in Taiwanese women aged 60 or over, face-to-face interviews with 1,517 women, selected by a multistage random method, were completed. The prevalence of UI in this age group was 29.8%. Factors and their prevalence associated with UI were age [odds ratio (OR)=1.04 per year], diabetes mellitus (39.8%, p = 0.002), hypertension (39.5%, p = 0.001), abdominal gynecological surgery (41.4%, p = 0.001), hysterectomy (42.4%, p = 0.003), history of drug allergy (41.3%, p = 0.001), smoking (45.5%, p = 0.010), hormone replacement therapy (41.5%, p = 0.026), and high body mass index (OR = 1.05 per unit). Alcohol consumption and marriage did not increase the risk of UI. UI is a common and costly problem in elderly women. It diminishes the quality of life of the affected women. Of the associated factors that are preventable, modifiable, or controllable, smoking, prior hysterectomy, and obesity may have the greatest impact on the prevalence of UI.

Risk factors for nocturia in Taiwanese women aged 20-59 years.

OBJECTIVE: To assess the risk factors for nocturia among Taiwanese women aged 20-59 years. MATERIALS AND METHODS: A random sample of 4,549 women aged 20-59 years was selected by multistage sampling. A total of 3,537 women were interviewed face-to-face by well-trained interviewers and local public health nurses. The definition of lower urinary tract symptoms used is that as defined by the International Continence Society. Variables of sociodemography, medical histories, obstetric and gynecologic histories, and lower urinary tract symptoms were recorded. The factors were assessed by frequency and logistic regression analyses using a significance level of less than 0.05. RESULTS: The prevalence of nocturia increased significantly with age (p < 0.001), body mass index (p < 0.001), diabetes mellitus (p = 0.024), hypertension (p = 0.001), previous gynecologic operation (p = 0.003), drug allergy (p = 0.036), and marital status (p = 0.000). However, there was no relationship between nocturia and smoking, alcohol consumption, parity, hysterectomy, menopause or hormone therapy. CONCLUSION: Although the answers to the etiology of nocturia are still not all known, nocturia has been associated with various factors, suggesting that multiple approaches are necessary in the treatment of patients with nocturia.

Prevalence of nocturia in Taiwanese women aged 20-59 years.

OBJECTIVE: To estimate the prevalence of nocturia in Taiwanese women aged 20-59 years. MATERIALS AND METHODS: A random sample of 4,549 women within the age range was selected by a multistage sampling design. Face-to-face visits with 3,537 women were completed by well-trained professional interviewers. Nocturia, according to the definition of the International Continence Society, and its associated problems were evaluated and, concurrently, variables of medical histories and sociodemography were recorded. RESULTS: The response rate was 77.8%, and a total of 930 of 3,521 women reported having had nocturia, producing a prevalence of nocturia of 26.4%, with 16 not answering the question about nocturia. For those who had nocturia, 88.9% of the interviewees reported < or = 2 voids per night and 1.6% of these women reported having to void > or = 5 times per night. CONCLUSION: Nocturia is a common condition among Taiwanese women, especially among the elderly. Its prevalence is significantly related to age. Treatment of this condition in this patient population can both improve their quality of life and reduce the risk of deterioration in their general state of health.

Risk factors for urinary frequency in Taiwanese women aged 20-59 years.

OBJECTIVE: To evaluate the risk factors for daytime urinary frequency in Taiwanese women aged 20-59 years. MATERIALS AND METHODS: In 1998, there were about 5.9 million female residents aged 29-59 years in Taiwan. A random sample of 4,549 women within this age group was chosen by multistage sampling. Face-to-face interviews with 3,537 women were completed by well-trained professional interviewers within 3 months of the subjects being selected. Answers to questions about lower urinary tract symptoms, sociodemography and past histories were recorded. The factors were assessed by frequency analysis and logistic regression analysis using a significance level of less than 0.05. RESULTS: The prevalence of daytime urinary frequency was significantly related to diabetes mellitus (p = 0.038), hypertension (p = 0.016) and previous gynecologic surgery (p = 0.005). However, there was no relationship between urinary frequency and body mass index, drug allergy, smoking, alcohol consumption, marital status, childbirth, parity, hysterectomy, menopause, hormone replacement therapy or age. CONCLUSION: The results of this study show relatively high risk of urinary frequency development in patients with diabetes mellitus or hypertension. Better quality health education of these women, drawing their attention to the possibility of gynecologic surgery, is the most important factor in making current gynecologic surgery more effective. In addition, more attention given to associated factors that are preventable, modifiable or controllable, for example diabetes or hypertension, may have an impact on the prevalence of urinary frequency.

Prevalence of urinary frequency in Taiwanese women aged 20-59 years.

OBJECTIVE: To evaluate the prevalence of daytime urinary frequency among Taiwanese women aged 20-59 years. MATERIALS AND METHODS: In 1998, there were an estimated 5.9 million female residents aged 20-59 years in Taiwan. A random sample of 4,549 women was chosen by multistage sampling. Face-to-face visits with 3,537 women were completed by trained professional interviewers within 3 months of the subjects' selection. Questions about lower urinary tract symptoms, sociodemographics, reproduction, and medical and surgical histories were recorded. The factors were assessed by frequency and logistic regression analyses using a significance level of less than 0.05. RESULTS: The prevalence of urinary frequency in Taiwanese women aged 20-59 years was 5.2% (182/3,519); 18 interviewees did not answer the question about frequency and were excluded. For those who complained of frequency, 47.2% voided 8-15 times a day, 37.4% voided 16-23 times a day, 1.1% voided 24-31 times a day and 14.3% voided more than 31 times a day. The prevalence of urinary frequency was not linked to age (p = 0.326). CONCLUSION: Urinary frequency is a common symptom in women of all ages and is not significantly related to age. More than half of the women interviewed admitted that less than an hour occurred between visits to the restroom during the daytime.